Actually, as someone who has designed/run a high scale REST API, I have a slightly blasphemous view on this - that the RESTful-ness of the API doesn't matter.

Actually, as someone who has designed/run a high scale REST API, I have a slightly blasphemous view on this - that the RESTful-ness of the API doesn't matter. You're better off trying to control how the various language bindings look like and focusing on making core scenarios be as clean as possible code-wise. That's what the developers building on top of your API will actually see and deal with on a day-to-day basis.